Emergency phone services are provided over landline phones as well as over wireless phones. Wireless emergency service may be referred to as e911. Federal law dictates that certain procedures be followed when handling e911 calls. One of those requirements is that a self-location determined by the originating mobile communication device be transmitted with the e911 call to the e911 handling station. This self-location may be performed by a global positioning system (GPS) radio receiver embedded in the mobile communication device.
Trilateration is a mobile communication device locating technique that is based on analyzing radio signals emitted by the mobile device and received by proximate cell towers. The received signals can be used to estimate the position of the mobile communication device.